In the past, espresso aficionados visited their local cafe for an expertly prepared drink on commercial equipment because making a decent espresso at home simply wasn't an option. Nowadays, the best cafes are as likely to be in the kitchen of a dedicated home barista as down the street, thanks to the availability of lower-cost high-quality gear and access to espresso-making knowledge through sites like this one. With the introduction of the mypressi TWIST, mobile espresso lovers have another option to consider.

The TWIST has received plenty of exposure in the past eight months, from winning Best of Show at the SCAA 2009 convention, through television appearances and magazine articles. The TWIST was officially launched in early November 2009. Dan and I have been using evaluation units for about three weeks in preparation for this Second Look. This review of the mypressi TWIST will unfold in regular installments.

UPDATE 11/16/2010 for TWIST V2:

Bottom line: The TWIST V2 shows better consistency shot to shot, simplified shot prep, and delivers quality espresso using four different coffees, from medium to dark roasts covering blends and single origin coffees. To read more details about the improvements, click here.

mypressi TWIST (photo courtesy Espressi, Inc.)

In a nutshell, the TWIST uses compressed gas (N2O) which travels through a pressure regulator to create 9 bars of pressure. The pressurized gas enters a water chamber full of preheated water and pushes the water through a dry coffee bed. There is no pump nor a boiler. A N2O cartridge, like the ones for whipped cream chargers, is used as the "pump". Instead of a boiler, the user preheats water in a kettle then pours it into the TWIST's water chamber.

The two main pieces of the TWIST are shown below. The basket drops into the portafilter ring and the water chamber locks and secures with a twist:

Water chamber inverted in photo to show dispersion screen (photo courtesy Espressi, Inc.)

The package includes a 53mm double basket, double pressurized basket, pod basket, and two dispersion screen assemblies, one for pods and the other for ground coffee. I assume none of the visitors to this site use pressurized baskets or pods, so we will leave those out of this review. A note worthy addition is a slew of replacement rubber O-rings. As we will see later, those spare rings come in handy.

Out of the Box (photo courtesy Espressi, Inc.)

Over the next month, Dan and I will introduce you to the TWIST; we'll evaluate the espressos' taste, offer dosing techniques and usage tips, and present a technical overview of the TWIST. To whet your appetite, below is a quick video showing it in action. Stay tuned...

I started the day with Ecco Caffe's Espresso blend. Following the user manual instructions, I preheated the brew chamber for 20-30 seconds with boiling water, dumped the water, refilled it with boiling water and pulled the trigger. It poured like it would from a prosumer machine, and did it in a whisper. What a welcome change from the earthquake-inducing noise of a standard vibe pump.

First shot - Ecco Espresso (photo by Andy Schecter)

A quick swirl to mix the brew and down it went. Ouch, that one was sour. For comparison, I used the same dosing and timing on my home prosumer espresso machine and pulled a shot. That one was balanced and nuanced. The temperature on my machine was 199°F. The prime suspect at this point is temperature. The TWIST's brew temperature may be too low for this coffee.

For the next shot, I focused on preheating the brew chamber. I filled it up with boiling water, let the water heat the chamber for 2 minutes, dumped the water, filled it up again with boiling water, let it heat for 30 seconds, dumped it, filled it up again and pulled the shot. A marked improvement. The shot was much more balanced, and the sourness drastically reduced. It was still not as rich as the shot I pulled on my home machine. In the USBC grading scale, it would be around 2, while the shot I pulled on my home machine would be around 3-3.5

Second shot - longer preheat of brew chamber (photo by Andy Schecter)

To try to improve the shot, I proceeded with changing the dose, keeping the grind as is. I updosed the next shot with 17.5 grams (from 16 grams) and pulled the trigger. I kept the timing at 26 seconds. The pour was slower and the shot lower in volume (about 1 oz) this would be a tight ristretto. A noticeable improvement. Better balance, a sweeter shot, creamy with soft acidity. If I got this shot in a coffee shop I'd say that's a decent shot.

Next I worked on grind adjustments, taking it up and down a notch, but that didn't improve the shot.
I have a few more featured coffees to go through, and I decided to share those with a group of friends that are coming by for a coffee get together this weekend. These are all "civilians" and their input should be interesting. I'll cover that meet in the next installment.

Yesterday's coffee meet started off with Belle Espresso from Klatch coffee. The TWIST received many accolades from the crowed for its graceful design and miniature size. My guests were all coffee lovers who are not as obsessed with perfecting a shot as some of us are, and just enjoy a good cup of espresso. After sampling a few shots from the TWIST the consensus was that it was delicious. In the words of one participant, "I don't think I had such good espresso in any coffee shop."

A few of the civilians. From left: Zvi, Sarah, Kohi & Abe

We proceeded with a cappuccino round pulled from my home machine, as I contemplated on the usage of the TWIST by the average consumer. What exactly is the market for this device? I will return to that question later in the review.

During this outing, the later shots I pulled on it tasted better, I assume because they were consecutive shots and benefited from better preheated metals. On Dan's suggestion, I also added to my prep routine preheating the ring of the portafilter (handle) in a small container of hot water to keep it warm. I'm not sure if it helped or not, but today's shots were better than the coffee I had on day one. Dosing changes also helped; a dose around 16 grams gave the best result.

Preheating the portafilter ring

Over the course of my tests, two of the O-rings on the device dislodged (one around the N2O exit port of the handle, and the other around the dispersion screen). The one around the shower screen may dislodge due to the pressure release when the unit is opened too quickly after a shot. I've developed a quick routine for placing the shower screen ring back in its groove using a chopstick. But the small O-ring around the port may also dislodge; if you don't pay attention, it will go down the drain as you wash the handle with water.

Misbehaving o-rings. Notice the small o-ring around the port at 6 o'clock.

The shower screen O-ring out of its groove

As the crowd dispersed, I proceeded with Counter Culture 21st De Septiembre blend. This one had the best shot at 15 grams, and a very tight grind. I noticed that when the grind is very tight, it is not a good idea to fill up the water chamber all the way to the top. The TWIST struggles to press the water through the coffee bed, and some gas starts escaping from the lid seal of the water chamber. Better to leave about 1/8th of an inch of air.

Lifting the mypressi TWIST out of the box, I was surprised by its heft. Its [dry] weight and balance reminded me of a commercial portafilter, like those made by La Marzocco or Rancilio. Although it is modeled after a stock portafilter, the lock-in tolerances between the water chamber and portafilter ring assembly is much tighter than one would expect between an espresso machine's portafilter and grouphead. The mypressi TWIST as a whole disassembles quickly and neatly with snappy precision.

Earlier Abe mentioned the O-rings sealing the various compartments of the TWIST. There are four of them:

O-ring underneath the water chamber cap to seal the fill opening,

O-ring around the dispersion screen assembly to seal between the water and brew chamber,

O-ring "group gasket" around the dispersion screen to seal against the basket's lip (shown below),

O-ring around the mating port to the pressurized cylinder (shown earlier).

The second O-ring listed above fits in a groove around the black plastic dispersion screen assembly shown below; its left/right tabs provide good grips for removal, should you want to replace it with the included pod-capable equivalent.

(Although not tested, the pod-capable dispersion screen and basket are markedly smaller in circumference and shallower than those designed for ground coffee. The two halves are designed to clasp tightly around the pod, forming a mini-brew chamber.)

Cleaning the TWIST is as easy as cleaning a normal portafilter - a quick rinse and wipe suffices. To clean it thoroughly inside and out, grasp the two black tabs of the dispersion screen assembly and pull. This exposes the interior of the domed water chamber for inspection or cleaning around the perimeter for the smudge of coffee that may appear after a half-dozen or so shots.

The end of the portafilter handle has a short threaded cap shaped to mate with the contours of the handle. Unscrewing it reveals the chamber that holds the N2O canister. The TWIST is delivered with four starter cartridges; to load, unscrew the end cap, insert the canister into the handle with the sealed nipple forward. As you tighten the end cap, the canister's end is punctured. Pulling the trigger releases the gas through the handle to the port surrounded by the tiny O-ring pictured earlier. Don't worry if you unscrew the cap while the canister is still pressurized -- the threads of the cap are grooved along their lengths on two sides so the pressurized gas will harmlessly escape long before the threads disengage from the handle.

To complete the tour of the mypressi TWIST construction, below is a cutaway of its internals:

One quality that is difficult to quantify but very important to those trying to choose among a wide array of espresso equipment is the so-called forgiveness factor. In the site's Buyer's Guides, this quality is called the "morning after" score and considers those who are learning and what they should reasonably expect in the early days following delivery. Or, to put it another way, a modestly skilled home barista using equipment that has a high morning after score is almost certain to reproduce the results described in another Buyer's Guide score, the "exceptional espresso" score.

Over the years, many people, including me, have tried to correlate some easily measurable metric that would predict an espresso machine's forgiving nature (or lack thereof). Thanks in part to the popularity of the E61 group and its built-in preinfusion (expansion) chamber, preinfusion in its many guises has been a leading candidate. Today I remain unconvinced it's the end-all be-all, though preinfusion does appear to improve the consistency of the espresso (for those interested in more background information, see the thread Pressure profiles, preinfusion and the forgiveness factor, which documents my failure to prove such a correlation).

Although I've sworn off making performance predictions based on measured metrics, I haven't given up my hunches. One factor that appears promising isn't easily quantified, but is reasonably easy to see: Even diffusion of brew water during the early wetting of the puck.

Returning to the mypressi TWIST, I noted from day one that it was very easy to dial in. Given a reasonably even distribution of the coffee grounds in the basket, dose in the range of 15 to 18 grams, level tamp, and a grind setting comparable with pump-driven espresso machines, the pours proceed smoothly and evenly (*). Given its design, I expected it to have exceptionally even wetting and it does, as this video demonstrates:

Note how evenly distributed the water is. This is very much a lever espresso machine's diffusion profile, i.e., basically a piston pushing a column of water through the dispersion screen. While there are many possible contributors to a given espresso machine's forgiveness factor, my hunch is that an even initial wetting, like the TWIST's, is a top contributor.

(*) Those among you crying out for a bottomless portafilter video featuring the mypressi TWIST are sure to find them on youtube. At some point before wrapping up this review, Abe and I will draw straws for who does the obligatory TWIST espresso porn.

The last two entries focused on the mechanics and construction of the mypressi TWIST. With those details out of the way, our attention turns to the all-important question: How well does it make espresso?

To answer this question, I enlisted the opinion of the attendees of Counter Culture Coffee's regular Friday espresso lab. The first session was very much a "getting to know you" experience. Having never used the TWIST before, I skimmed the owner's manual and then starting making espresso. The second session was more practiced, but like the first, focused on polishing technique rather than critiquing the quality of its espressos. The third session introduced a formal blind taste test using a Counter Culture espresso blend which was very familiar to all of the tasters. The final session is planned for this Friday and will feature an unfamiliar single origin espresso.

Below are my notes from these three sessions; the following post documents the fourth and final session.

SESSION 1:

My very first impressions of the mypressi's shots were reminiscent of those I would expect from a spring-powered lever espresso machine: Smooth, rounded, and simple. The two shots of Counter Culture Forte, which is their darker milk espresso base, usually has some edge to it, yet they were "fluffy" in texture with a mellow flavor profile.

As I narrowed in the proper grind setting, subsequent espressos showed slight tiger striping, greater body, richer texture, and longer pours before blonding. Definite espresso characteristics of body, oiliness, etc. As the TWIST heated up, its espressos gained the slight bite on the finish I expected for this blend and roast. If this were competition, the espressos in the first session would be 2's (see What does your typical espresso rate? for explanation of scoring). Others pulled from the resident La Marzocco FB-80 outscored the TWIST by at least a full point, consistently hitting the 3.0 to 3.5 range. Despite its defeat by the former WBC equipment, there's no arguing that the TWIST's espressos were not "real" espressos.

SESSION 2:

This time around, we chose a more challenging single origin, Counter Culture's 21st de Septiembre. Unlike the espresso blend in the first session, this single origin will zig more markedly when the temperature zags. Also keep in mind that single origin espressos are prized for the varietal character versus the crowd-pleasing "chocolate bar" blends that dominate mainstream roasters' signature offerings. As in the first session, the TWIST performed respectably in two rounds, but lost to the home team by a similar spread. However, thanks to our practice, it moved up in consistency, so we agreed to do a blind taste the following week.

SESSION 3:

Below is a video from this session showing the simultaneous extractions for the blind taste test. Sorry about the poor quality of the video, I didn't realize until after the fact that the camera was in low-res mode; however, it gives you an idea of how we did the test:

Note: The La Marzocco pulled tighter than expected for this pair, so the dose was reduced slightly in subsequent rounds for a closer brew ratio.

Protocol: We used identical cups and presented them to a taster for evaluation. There were asked not to look for any visual clues since the TWIST espressos had greater volume with less striping than the La Marzocco's. The TWIST's portafilter ring was preheated in a pitcher of hot water; the brew chamber was filled with boiling water, dumped, and filled again.

This session was by far the best showing for the TWIST. Below are participant comments (paraphrased):

Tim wrote:Both espressos were good. The TWIST espresso is slightly brighter. The La Marzocco edged it out on creaminess. I picked the TWIST's espresso as my preference one time and the La Marzocco the other; overall I would place them within 0.5 point of each other in both rounds.

Bob wrote:Overall, I agree that they were within 0.5 points. Depending on preference for brightness, one may actually prefer the TWIST. I think it would be a great solution for vacationers in a cabin or cottage setting (versus a motel and on the road a lot).

Dan wrote:This coffee would be better after another day or two of rest, but for this test, it was basically a draw. Last time we used the brighter and more demanding single-origin 21st de Septiembre. The TWIST lost every round in that case by a full point. It's too early to draw conclusions, but I wonder if the temperature tolerance of mainstream blends leveled the playing field for the mypressi.

Nathan wrote:The TWIST espresso was brighter in both rounds. It was a good espresso, but I don't understand who is the target audience. Campers who want an espresso in the woods? A cheap alternative to an entry-level espresso machine? Office workers? [interesting discussion of market followed]

HINTS AND TIPS:

The handle soaking trick may help in spaced shots, but heating the chamber with it in the ring seems to accomplish the same end if you wait a bit longer than the recommended 20 seconds.

TIP 1 (experimental): Assemble the chamber/ring without the basket and place the grouphead in an inverted Mazzer doser lid or similar shallow plastic container. Then fill to overflowing to preheat the dispersion screen and water chamber. Loosely place the lid on. Prepare the basket as usual. Empty and refill shy of the top of the chamber before pulling the shot.

TIP 2: I found it helpful to slowly pour the water out by tilting the chamber over with it engaged in the portafilter ring. But be careful! Double-check that the chamber is engaged by confirming the tiny "notch" is aligned with the lock-in position since the chamber is not snugly held to the ring unless the basket is in place.

Just to make life interesting, we held a single origin espresso shootout this morning at Counter Culture Coffee's regular Friday espresso lab.

SESSION 4:

This session featured another round of blind taste tests, this time with a single origin espresso under development. The result? Surprisingly, against the resident La Marzocco FB-80, the diminutive TWIST won every round with three blind taste testers. We really liked this SO... a huge fruit bomb. Think blueberry pancakes with light maple syrup. To get similar pour speeds from the two machines, we dosed the LM at 19 grams and the TWIST at 22 (!!) grams and pulled 1+ ounce ristrettos.

Here's some background info on the test coffee from their website, though it's for the drip/brew roast:

Lovingly hand picked and sun dried by the skilled farmers of Shakisso, this intensely flavorful natural-process coffee shines with bright notes of ripe berries above luscious chocolate undertones. Just as with our washed-process lot from Shakisso, this natural sundried coffee is made up of both cultivated and wild coffee varieties, resulting in a remarkably complex cup bearing the attributes of each.

The head roaster is still tweaking the profile and thus the espresso tasting notes will change over the next month. As I understand it, this will replace the current 21st de Septiembre single-origin Espresso in early January.

With a month of using the TWIST behind me, I stepped away for a few hours from evaluating the espresso it makes, and put my propeller hat on. Today's installment is about measuring the mypressi TWIST brew temperature. But before we get to it, the following primer is required to put the results in perspective.

In the early days, circa 2004, when espresso brew temperature was all the rage, members of the online espresso community spent a lot of time obsessing over it and building crude devices for measuring it. In time we've learned that measuring the brew temperature of an espresso extraction is a non-trivial exercise. There are many factors at play when water goes through the coffee bed under pressure and they cannot be accurately captured by a single probe. Within this limitation, we settled on measuring the water temperature as it hits the coffee bed. Greg Scace put us all out of business as amateur probe builders when he introduced the thermofilter device, which measures water temperature as it exits the dispersion screen during a simulated shot (no coffee is used). The Scace became the official brew temperature device of the WBC & USBC, and is widely used in the professional community today to test and calibrate espresso machine brew temperature (see WBC Procedure for Measurement of Brewing Water Temperature for details).

Unfortunately for my test, the Scace fits the standard professional and prosumer 58mm espresso machines, but not the 53mm Mypressi TWIST. So, to measure brew temperature, I setup a poor man's water temperature measuring device. Not as accurate, but something that works on the same principle, and has been used for years by home-baristas to measure water temperature: I stuffed the TWIST pressurized basket with aluminum foil, shaped it as a small bowl, so that there would be an indentation in the middle of it. I snaked a thermocouple probe into the TWIST basket, placed it in the center "bowl", and locked the water chamber. The probe was now locked in position and ready for the test. A pressurized basket is a regular basket but with only one small hole in it. Since no coffee is used, I wanted to create a flow rate similar to a real extraction, and the one hole basket with the crumpled aluminum foil in it does it nicely.

I conducted two tests. One measuring water temperature in the water chamber during a period of 30 seconds, and the other measuring "brew temperature" during a simulated extraction.

TEST 1: Measuring water temperature in the water chamber.

Following a suggestion from Stephen O'Brien, Mypressi president & inventor, I used the following routine to preheat the water chamber in preparation for the test:

Fill water chamber with boiling water.

Let sit for 30 seconds, empty chamber and repeat.

Refill it again with boiling water and measure temperature.

Below is a video documenting the test.

Result: By the time the chamber lid is closed, water temperature has dropped to 201°F. Within 7 seconds, it is down to 195°F, and after 30 seconds it reaches 190°F.

TEST 2: Measuring "brew temperature" during a simulated extraction. Preparation was the same preheating routine as in Test 1.

Result: The brew temperature starts at 190.6°F and ends after 24 seconds at 187°F. Average brew temperature is around 189°F.

The average brew temperature we've measured in prosumer and commercial espresso machines is around 200°F; that is also the temperature required by the USBC and WBC. As shown in the tests above, the mypressi TWIST's brew water temperature is markedly lower. Given the crude method used to measure it, there could be a couple of degrees of wiggle room there, even so the brew temperature is lower than the temperatures we typically measure when evaluating conventional espresso machines (*).

And yet the mypressi TWIST can produce very nice espressos. This suggests there may be other factors unique to the TWIST's mechanics that favors its performance at lower brew temperatures than we would expect from more traditional espresso machines. We'll return to this point before wrapping up the review.

BREW PRESSURE:

I think the only thing left to dissect on the TWIST is its pressure profile. To that end, Hayri Sönmez comes to the rescue. He retrofitted a basket with a pressure gauge and pulled a shot. The TWIST ramps up pressure to 9 bars in ~9 seconds and then stays at 9 bars to the end of the shot.

HINTS AND TIPS:

I tried the following technique suggested in an email by Hayri Sönmez, one of our forum members. Before I pulled the shot, I used the steam wand on my espresso machine to further heat the water in the water chamber, then closed the lid and pulled the shot. It significantly raised the brew temperature with the shot peaking at 196.7°F. My taste buds also confirmed the flavor profile of a hotter brew temperature when following this tip for a real extraction. While not tested, presumably a stove top steamer available at ~$60.00 could be used for this purpose, since those who drink milk drinks would need one anyway to go along with the TWIST.

(*) As to the accuracy of the test, I used the same crude method on my home machine and recorded brew temperature around 198°F when the machine brew temperature was set to 200°F.

When we started this review, the mypressi TWIST, a unit that costs $169 and is slightly larger than a portafilter on a commercial machine, faced what looked like an insurmountable challenge against my home espresso machine - a PID controlled dual boiler prosumer, 20 times its size. After using the unit for a month, that little engine made it all the way to the top without breaking a sweat. It makes very good espresso, different in character from a pump driven machine, but the quality is just as good. It does not have the brew temperature control and range of a standard espresso machine, but I cannot argue with the final quality in the cup. The shots pour, look, smell and taste like real espresso, and more closely resemble lever driven than pump driven machines. The TWIST may not be as comfortable with as wide a range of coffees as a standard machine-- I suspect it has to do with its brew temperature range --but the great majority of coffees sold for espresso today will do very well on the unit.

Pros:

Makes very good espresso - on par with much larger and expensive prosumer espresso machines.

Tiny alignment indentation on water chamber for locking in is difficult to see and not easy to feel.

Minor points such as soggy pucks and no steaming capability.

FINAL TIP:

The unit may suffer from soggy pucks after a shot. To get a less soggy puck (which makes cleanup easier), I place the TWIST in an angle using its inverted spout attachment on one side, and a little dish on the other. It drains some of the excess water before I open it up and knock off the puck.

The TWIST placed at an angle after a shot to drain excess water from the puck

First of all, I would like to express my appreciation to Abe for taking on this review. Being the holiday season, it's doubtful that I could have mustered the enthusiasm, but he did the heavy lifting and left most of the "fun" to me. Thanks Abe!

For me, the mypressi TWIST, which at first appeared interesting to only gadget freaks, has turned out to be an enigmatic challenge. As Abe documented in the temperature tests, professional baristas and experienced home baristas would expect the TWIST's lower brew temperature to be detrimental to shot quality. And yet qualified participants in blind taste tests using wildly different coffees struggled to discern the espressos prepared with the mypressi TWIST from those prepared with the WBC-qualified La Marzocco FB-80.

Whether this accomplishment is a tribute to the skills of the roaster, the efforts of the people who sourced such exceptionally consistent coffees, the top-end grinders employed, or an innovative combination of the mypressi TWIST's design features is fodder for future speculation. In addition to its impressive performance as an espresso machine (it sounds funny to write "espresso machine" for a device not much larger than a portafilter!), I look forward to the rethinking of accepted barista wisdom the diminutive TWIST is certain to provoke.